A cellular network or mobile network is a network distributed over different land areas, which are called radio cells. Each radio cell is each served by at least one fixed-location base station. In the cellular network, each radio cell uses a different set of frequencies in relation to its neighboring radio cells in order to avoid interference and provide guaranteed bandwidth within each radio cell. In this traditional setup of cellular networks there are no problems with interference, since neighboring radio cells use different frequencies.
Lately the development of heterogeneous networks using combined radio cells, also called shared radio cells, has increased rapidly. In heterogeneous networks or shared radio cell environments a radio macro cell covering a large area is complemented within said large area with for example radio pico-cells served by pico-base stations. The combined radio cell cellular network allows operators to configure multiple radio cells with partially overlapping coverage as one ‘radio cell carrier’. The same downlink signal is transmitted on each downlink radio channel, and the uplink signal is jointly decoded from the different radio cells. These radio pico-cells may be used to cover blind spots underneath a macro sector, or to minimize the number of separate radio cell carriers required in coverage limited scenarios. Compared to separate radio cells, the shared radio cell may have fewer radio cells in the Radio Network Controller, RNC, less mobility signaling, and smooth radio cell split if traffic increases.
However, one drawback with this setup is that all User Equipments, UEs, belonging to the same combined or shared radio cell, i.e. either the radio macro cell or any of the radio pico-cells within the radio macro cell, have to share the same uplink load resource in this combined radio cell. With Time Division Multiplexing, TDM, scheduling, the chance for each UE to be scheduled without increased transmission latency and delay will decrease. This is due to the fact that the number of the served users in a shared radio cell environment is much greater than in a traditional cellular network. The shared radio cell environment will thus contribute to increasing connectivity for UEs, but may also create a bottleneck if there are many UEs within the shared radio cell environment. Thus, it would be great if one could use the shared radio cell environment without the drawback of increasing transmission latency and delay.